Generally, the fluid pump of the present invention is an improvement over pumps shown U.S. Pat. Nos. 4,553,512, 4,875,551 and 4,502,431. These pumps are used to lubricate the engine prior to the initial phase of the cranking of the starter motor to turn over an engine. Typically, oil is used as a lubricant to allow engine parts to slide freely and easily with reduced friction. Notwithstanding the use of lubricants having high lubricity there continues to be abrasive wear between metal parts in internal engine components such as the turbocharger, camshaft, crank shaft and rocker assembly, for example. It has been known for some time that the greatest wear on internal engine parts is at the commencement of ignition cranking and engine start-up. During that time, there is insufficient oil pressure in the engine to provide lubrication to the various parts throughout the engine. Accordingly, for these initial moments during start-up, there is metal rubbing against metal without a sufficient lubricant interface so that deterioration in the internal engine components takes place over time.
A particularly important solution to this problem was provided by a prelubrication system disclosed in U.S. Pat. No. 4,502,431 in which oil is introduced in the engine prior to cranking and start-up. The starter motor is utilized as the means for powering the pump to provide prelubrication. In that system, the starter motor armature shaft is connected to the pump's pumping gears which are rotated to provide the pumping action to the engine to prelubricate prior to the starter motor's solenoid engaging the starter to crank the engine for start-up. One particular embodiment of the starter motor and pump combination is disclosed in U.S. Pat. No. 4,553,512 which is incorporated herein by reference.
The present invention provides a similar pump assembly as that disclosed in U.S. Pat. No. 4,553,512 to provide a selectable means for either prelubricating the engine or pumping the oil out for a quick efficient oil change. This is particularly useful to large fleet operators of vehicles which require frequent oil changes.
Accordingly, it is an object in an embodiment of the present invention to provide a pump mechanism to pump oil out of an engine sump without having to open the sump's oil plug. It is a further object in an embodiment of the invention to provide a seal bore vent to the pump inlet to minimize the oil pressure at the seal during all modes of operation. Another embodiment of the invention is to provide a supplemental pump on-board for evacuating and/or refilling multiple reservoirs, or in a hand-held device that may be used for multiple reservoir evacuation and/or refill. It is a further object in an embodiment of the invention to provide a prelube pump having a valve which is selectively operable in the prelubrication mode as well as an oil exchange mode from the engine compartment.